To face the global sustainability issues arising from rapid industry development and population increase, many efforts have been made to develop new materials and technologies toward renewable energy and environmental improvement. Zeolites are a family of crystalline materials with orderly distributed micropores in molecular dimensions. As the most important solid catalysts used in traditional petrochemical industries, zeolites are also finding promising applications in many sustainable processes given their unique shape selectivity, adsorption and ion-exchange capability, high hydrothermal stability, tunable acidity and polarity, and low production costs. In this review, we present the state-of-the-art applications of zeolites as potential solutions to the sustainability issues, including biomass conversion, fuel cells, thermal energy storage, CO 2 capture and conversion, air-pollution remediation, and water purification, etc.

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A series of TiO 2-reduced graphene oxide (rGO) coated side-glowing optical fibers (SOFs) were synthesized by polymer assisted hydrothermal deposition method (PAHD), and characterized by crystallographic and spectroscopic methods. Fourier transform infrared spectroscopy showed that the mixed graphene dioxide (GO) was reduced during PAHD coating of TiO 2-GO nanocomposites. X-ray diffraction patterns revealedTiO 2 presentedas a mixture phaseof anatase, rutile and brookite in the TiO 2-rGOnanocomposites. UV-visadsorption spectra of TiO 2-rGOnanocompositesindicated that mixing rGO into TiO 2 particles could reduce band gap energy, thereby enhancing utilization efficiency of visible light. Photocatalytic performance of the synthesized nanocompositeswasmeasured by the degradation of three pharmaceuticals under UV and visible light irradiation, including carbamazepine, ibuprofen, and sulfamethoxazole. TiO 2-rGOnanocomposites exhibited significantly higher photocatalytic activities as compared to pure TiO 2 , and were strongly affected by the amount of rGO in the catalysts. While photocatalysis with 2.7%rGOachieved54% degradation of carbamazepine, 81% ofibuprofen, and 92% ofsulfamethoxazole after 180 min UV irradiation, the mineralization rates of the pharmaceuticals were similar between 52% and 59%. The photocatalytic oxidation of pharmaceuticals by the prepared nanocomposites followed the Langmuir-Hinshelwood kinetic model. There was an obvious positive correlation between degradation rate constant and quantum flux for both UV and visible light, with correlation coefficient of 0.991. In addition, long-term photoactivity testing of TiO 2-rGO coated SOFs demonstrated thedurability of the immobilized TiO 2-rGOnanocomposites on optical fibers for water treatment.

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Scale deposits in water systems often result in ample technical and economic problems. Conventional chemical treatments for scale control are expensive and may cause health concerns and ecological implications. Non-chemical water treatment technologies such as electromagnetic field (EMF) are attractive options so the use of scale inhibitors, anti-scalants, or other chemical involved processes can be avoided or minimized. Although there are demonstrated beneficial effects of EMF on scale control, the scientific basis for its purported effectiveness is not clear in the available literature, especially lack of quantitative assessment and systematic evaluation of the effectiveness of EMF technologies. This review aims to elucidate the factors pertaining to EMF water treatment and their anti-scaling effects. We have critically reviewed relevant literature on EMF scale control, in particular recent studies, in various water systems, including desalination membranes, heat exchangers (e.g., cooling towers), water pipes, and bulk solutions. We systematically studied the impacts of operational conditions on EMF efficacy, and quantitatively evaluated the EMF improvement on scaling control. The scaling prevention mechanisms, conventional and cutting-edge characterization methods, and potential real-time monitoring techniques are summarized and discussed. The economic benefits of EMF treatment in terms of chemicals, operation and maintenance costs are highlighted. This review provides guidelines for future EMF system design and points out the research needed to further enhance EMF treatment performance.